镍基定向组织结构合金涂层的制备及性能研究

发布时间：2018-06-24 06:46

本文选题：Ni60 + SAPS　；参考：《兰州理工大学》2016年硕士论文

【摘要】：近年来,由难熔性材料制备成的保护涂层越来越多的是通过优点较多的超音速等离子喷涂(SAPS)方式来制备的,例如金属基耐磨耐蚀、热障陶瓷涂层等,但是发现由于涂层形成过程受工艺及参数限制,涂层中仍然存在着组织缺陷、内聚力低及结合强度不足的问题,这不但使得喷涂层的应用场合受限而且也缩短其使用寿命。因此,研究者们试图采用不同的制备工艺或者添加不同尺寸硬质相、稀土、自润滑相等方式来解决上述问题。在合金研究过程中,定向晶因其很大程度上改善了材料的纵向力学性能和物理性能,所以一直备受研究者和生产者的关注。因此,本文试图将SAPS、高频感应重熔技术、定向强制冷却三种工艺进行复合,在原始成分不变的条件下,通过在冶金结合的涂层中制备出致密的定向组织结构,来使得保护层的使用及工艺性能得到改良,尤其是摩擦和磨损特性。本文通过SAPS方式,使得Ni60涂层被预制在45#钢基材上,然后利用定向冷却装置在不同流量冷却水的作用下,对涂层进行感应处理+定向强制冷却。通过金相显微镜、SEM(EDS)、XRD、EPMA、宏观洛氏硬度和微观硬度测试仪器、万能摩擦磨损实验机等手段探究和测试了不同流量冷却水对感应重熔涂层组织和相演变、元素分布、使用及工艺性能的影响。利用Origin 7.5、Jade 6.5、Image-pro plus 6.0等相关软件分析了涂层的物相种类及孔隙率等。根据涂层的组织结构、物相、元素分布的演变分析结果,可以得出:随着冷却水流量的不断增大,涂层的组织结构发生了极大改变,涂层与基材之间均形成了一条明显冶金结合带。当冷却水流量为20、80、120L/h时,定向的柱晶出现在涂层中,其中当流量为80L/h时,涂层中形成的柱状晶结构比较致密细小,并且该涂层表面“十”字形的柱状晶中心对称性最好,并且柱晶偏离[001]方向的角度θ值最小,仅在0°~8°之间,而且沿((200)晶面)取向程度最高,即该冷却条件下,涂层中形成的定向组织相对比较良好;喷涂涂层的物相主要为γ-Ni、Fe Ni3、Ni2.9Cr0.7Fe0.36、Cr23C6、Cr2B、Fe3B,感应重熔后出现新相γ-(Fe,Ni)替代Fe Ni3相,其余相基本不变,感应重熔强制冷却涂层物相为γ-Ni、γ-(Fe,Ni)、Ni2.9Cr0.7Fe0.36、Cr C、Cr B等;元素分布表明初始柱状晶处主要富集Ni、Fe元素,而晶粒之间主要富集着的大量硬质相构成元素,强化了柱晶,对耐磨性有利。涂层性能研究结果表明:喷涂组织涂层截面显微硬度沿45#钢涂层方向,先增大后减小,而高频感应重熔组织涂层和定向组织结构涂层的显微硬度却小幅增加,并且二者的截面微观及表面宏观硬度均低于预制Ni60涂层;感应重熔后预制涂层的孔隙率从2.45%降低为0.59%,而定向组织结构涂层的孔隙率最小为0.23%;室温干摩擦条件下,随着载荷的增加,三种不同组织结构涂层与1Cr18Ni9Ti对磨的过程中,定向组织结构涂层的磨损量及磨损率均最低,表明其耐磨性优于其他两种涂层,并且和喷涂涂层摩擦系数相比,其摩擦系数有小幅增加,即阻摩特性有所增加。除此之外,喷涂涂层的主要磨损方式为疲劳剥落+粘着涂抹,感应重熔涂层的主要磨损方式为粘着涂抹+轻微剥落,定向组织结构涂层主要以粘着涂抹为主。
[Abstract]:In recent years, more and more protective coatings made from refractory materials have been prepared by a high number of supersonic plasma spraying (SAPS), such as metal base resistance and corrosion resistance, thermal barrier ceramic coating, etc. but it is found that the coating process is limited by the process and the number of parameters, and the cohesive force still exists in the coating. The problems of low and low bonding strength not only restrict the application of the spraying layer but also shorten the service life of the coating. Therefore, the researchers are trying to solve the above problems by using different preparation processes or adding different sizes of hard phase, rare earth and self lubrication. In the process of alloy research, the directional crystals are to a great extent. The longitudinal mechanical and physical properties of the material have been improved so much attention has been paid to the researchers and producers. Therefore, this paper attempts to compounded the three processes of SAPS, high frequency induction remelting technology and directional forced cooling. Under the condition of constant original composition, the dense directional tissue junction is prepared by the metallurgical bonding coating. To make the use and process performance of the protective layer improved, especially the friction and wear characteristics. In this paper, the Ni60 coating was prefabricated on the 45# steel substrate by SAPS, and the coating was induced and directed forced cooling by the directional cooling device under the action of different flow cooling water. Through metallographic microscope, SEM (ED) S), XRD, EPMA, macroscopic Rockwell hardness and microhardness tester, universal friction and wear test machine, etc., explore and test the influence of different flow cooling water on Microstructure and phase evolution, element distribution, use and process properties of induction remelting coating. Using Origin 7.5, Jade 6.5, Image-pro plus 6 and other related software, the coating materials are analyzed. According to the microstructure, phase and element distribution of the coating, it can be concluded that the structure of the coating has been greatly changed with the increase of cooling water flow, and a clear metallurgical bonding zone is formed between the coating and the base material. When the cooling water flow is 20,80120L/h, the directional column is made. When the flow rate is 80L/h, the columnar crystal structure in the coating is compact and fine, and the "ten" shape of the columnar crystal has the best center symmetry, and the angle theta value of the columnar crystal deviates from the [001] direction, only at 0 ~8 degrees, and the orientation degree along ((200) surface) is the highest, that is, the cooling bar. The orientation structure formed in the coating is relatively good, and the main phase of the coating is gamma -Ni, Fe Ni3, Ni2.9Cr0.7Fe0.36, Cr23C6, Cr2B, Fe3B, and the new phase gamma (Fe, Ni) is replaced by the Fe Ni3 phase after remelting, and the other phases are basically the same. The initial columnar distribution shows that the initial columnar crystal mainly enriched Ni and Fe elements, and the main content of the hard phase between the grains was enriched, which was beneficial to the wear resistance. The results of the study on the properties of the coating showed that the microhardness of the coating section of the coating first increased and then decreased along the direction of the 45# steel, while the high frequency induction remelting coating was used. The microhardness of the directional microstructure coating increased slightly, and the micro and surface macro hardness of the two sections were lower than the prefabricated Ni60 coating; the porosity of the prefabricated coating decreased from 2.45% to 0.59% after induction remelting, while the porosity of the directional microstructure coating was 0.23%, and three kinds under the dry friction condition, with the increase of load. The wear rate and wear rate of the coating are the lowest in the coating of different tissue structure and 1Cr18Ni9Ti, indicating that the wear resistance of the coating is better than the other two kinds, and the friction coefficient of the coating is increased slightly compared with the friction coefficient of the spray coating, that is, the friction resistance characteristics increase. In addition, the main wear side of the coating is the coating. The main wear mode of induction remelting coating is adhesive smear + slight peeling, and the main coating of directional tissue structure is mainly adhesive smear.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4

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